The GLORIA Master Site Schrankogel, Stubaier Alpen, Tyrol, Austria

The first GLORIA Master Site dates back to 1994, when an extensive
setting of permanent plots, arranged in transects across the
alpine-nival ecotone was established at Mount Schrankogel in the central
high Alps of Tyrol. These permanent plots were setup in response to
evidences on upward shifts of alpine plants on high peaks of the Alps,
reinvestigated in 1992 and 1993 (GOTTFRIED et al. 1994; GRABHERR et al.
1994, 2001; PAULI et al. 2001).

The 3497m-peak Mount Schrankogel belongs to the highest mountains of the
Austrian Alps. Its northern and eastern side is surrounded by glaciers
and
glacier forelands. Its southern to western faces, however, are not
interrupted by glaciers, but, show an altitudinal vegetation sequence
characteristic
for the central siliceous high Alps: from the lower-alpine zone,
dominated by dwarf shrubs, to upper alpine Carex curvula-grassland, and
finally to open
and scattered nival vegetation on screes and solid rock.

Around 1000 permanent plots, established
in 1994, are distributed between 2900m and 3450m near the summit area,
spanning across the alpine-nival ecotone from the upper margin of closed
alpine grassland to the nival zone. Alpine grassland, dominated by
Carex curvula and Oreochloa disticha, disintegrates within this ecotone
to open scree and rock-dominated plant assemblages composed of subnival
and nival cushion plants (e.g., Androsace alpina, Saxifraga bryoides),
small rosettes (e.g., Ranunculus glacialis) and graminoids (e.g., Poa
laxa, Luzula spicata).

Permanent plots of 1x1m were arranged in transects on the mountain's south-western
slope, at its southern,
south-eastern, and
eastern ridges.
Positions of the corner points of each quadrat were accurately surveyed
by using a tachymetre and photographs were made from each plot.
Percentage cover of all vascular plant species and total percentage cover of bryophytes
and lichens as well as the cover of abiotic surface components were
recorded. Further, a Digital Elevation Model of 1x1m-resolution, covering the entire study
area, was generated.

Between 1994 and 2011, a number of additional studies were added to the
extensive basic dataset of Schrankogel:
Besides an area-wide vegetation mapping
(ABRATE 1998; DULLINGER 1998) and a description of subnival to nival
plant assemblages (PAULI et al. 1999), model studies on vegetation
distribution and
patterns in relation to the macro- and micro-relief and micro-climate
were conducted (GOTTFRIED et al. 1998; GOTTFRIED et al. 1999, 2002).

Based on these
studies, scenarios of future distribution patterns of keystone species
were developed. Scenarios for the currently common nival species
Androsace alpina,
for example, suggested a drastic area losses due to climate warming.

Further, the influence of domestic and wild-living ungulates (ERTL et
al. 2002; HUELBER et al. 2005), nitrogen gradients (HUBER et al.
2007), permafrost
patterns (HAEBERLI et al., unpubl.), flowering phenology and
photoperiodism of alpine and nival vascular plants (KELLER & KÖRNER
2003; HUELBER et al. 2006),
as well as patterns of bryophytes (HOHENWALLNER et al. 2002) were
investigated. One of the most important additional dataset for the
analysis vegetation development
at the Schrankogel Master Site are temperature time-series, measured at
around 40 positions distributed over the mountain's southern slope
system since 1997.

What were the most obvious changes at Schrankogel's alpine-nival ecotone between 1994 and 2004? A re-investigation
of a representative one third of the Schrankogel permanent plots showed the following (PAULI et al. 2007):

Declining patches of Saxifraga bryoides.

(1) the vascular plant species richness has
significantly increased in the 1x1m-quadrats; the observed magnitude
of this increase was consistent with earlier studies from high summits of the Alps
(GRABHERR et al. 1994; PAULI et al. 1996; GRABHERR et al. 2001; BAHN & KÖRNER 2003; WALTHER et al. 2005);
(2) the species numbers have increased significantly more in plots which were formerly described as open subnival
and nival vegetation (PAULI et al. 1999) compared to plots with alpine grassland vegetation;
(3) the increase in species richness was mostly due to species which were already present in the elevation zone and
not due to invasion of species from lower altitudes; this 'filling process' rather than upward-migration is
explained by the fairly homogenuous grassland belt which may act as a barrier to invasion by lower-elevation species;
similar effects were observed on Piz Linard in Switzerland (PAULI et al. 2001, 2003).
(4) some alpine species and alpine to subnival pioneer species of have increased their cover, whereas all ‚true nival'
showed a decline. See (PAULI et al. 2007) below for details.

The observed changes on Mount Schrankogel confirmed data-based model
scenarios on climate-induced impacts on high-mountain plants (GOTTFRIED
et al. 1998; GOTTFRIED et al. 1999, 2002) and showed - for the first
time in the European Alps - signals of declines of the most cold-adapted
species.

As a cooperation with climatologists of the University of Vienna
(Research Platform "Mountain Limits") we recently analysed the
relationship between the alpine nival ecotone and the summer snowline.
Results showed that these to ecological/climatological lines coincide
strongly and that both lines moved upwards during the last decades
(GOTTFRIED et al. 2011).

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